1. Field of the Invention
The present invention relates to an air conditioning apparatus and an air conditioning method for reducing a pressure loss of circulation air to reduce electric power consumption for circulating circulation air in the air conditioning apparatus.
2. Description of the Related Art
A method for manufacturing a semiconductor device needs a process of using a hyperfine machining treatments. Associated with this process, dust existing in manufacture space for the semiconductor device invades the semiconductor device at a process of manufacturing the semiconductor device, and this invasion may cause the semiconductor device to be defective. Also, the change of temperature or humidity in the manufacture space may cause slight curvature or distortion to be incurred in a material used for the manufacture, which thereby may cause the semiconductor device to be defective. For dropping the rate of the defective device, it is necessary to reduce the quantity of the dust existing in the manufacture space and also necessary to keep the temperature and the humidity in the manufacture space constant. In response to above-mentioned request, the space is developed which is referred to as a clean room where the dust is reduced as much as possible and the temperature and the humidity are kept constant.
FIGS. 1A and 1B show a conventional clean room air conditioning apparatus using a FFU (Fan Filter Unit). FIG. 1A is a front section view showing this conventional clean room air conditioning apparatus. FIG. 1B is a side section view showing this conventional clean room air conditioning apparatus.
Referring to FIGS. 1A and 1B, the conventional clean room air conditioning apparatus using the FFU is provided with FFUs 41, a clean room interior 42, an under-floor portion 43, a cooling coil 44, and a return shaft 45.
FFUs 41 are set on a top surface of a clean room interior 42. A cooling coil 44 is set in an under-floor portion 43 of the clean room. A return shaft 45 is set outside the clean room for controlling a temperature of air passing through the cooling coil 44.
In the conventional clean room air conditioning apparatus using the FFU, the air is circulated in an order of an air flow 401, an air flow 402, an air flow 403 and an air flow 404 shown in FIG. 1A.
Refer to FIGS. 1A and 1B, the operation of the clean room air conditioning apparatus using the conventional FFU will be described below.
At first, air cleaned by the FFUs 41 is perfectly passed through the clean room interior 42, the under-floor portion 43 and the cooling coil 44. The air is cooled when the air passes through the cooling coil 44. The temperature of the cooled air is controlled by the return shaft 45 and returned to the FFUs 41.
The air conditioning apparatus according to the conventional technique shown in FIGS. 1A and 1B has a problem that a pressure loss of the circulation air in the clean room is large. One of the reasons is that the circulation air perfectly passes through the cooling coil which has the large pressure loss, when the quantity of circulation wind is determined not for cooling heat generated in the clean room but for keeping a room clean at a certain degree.
Also, this has a problem that a pressure loss outside the FFUs set on a ceiling surface is large to thereby cause energy required by the FFUs to be large. The reason is that a fan set in the FFU generates a wind pressure to compensate the pressure loss resulting from the air circulation. Thus, the pressure corresponding to the large pressure loss generated when the air is passed through the cooling coil is also attributed to the wind pressure generated by the fan.
Moreover, another conventional techniques with regard to the clean room air conditioning apparatus will be described below. At first, Japanese Laid-Open Patent Application (JP-A-Heisei 4-103937) describes "Method for Controlling Wind Quantity of Clean Room". This conventional technique has the following feature. A fan motor of FFU is composed of a single-phase motor in which rotation speeds can be changed in a plurality of stages by an operation of tap changing. An operational terminal unit for carrying out an ON-OFF operation and a tap changing operation of the single-phase motor is mounted for each FFU. A transmission line is laid for transmitting an operational command to each operational terminal device. The drive number of FFUs and the blown-out wind speeds from the FFUs are controlled through the remote operations of those operational terminal devices.
Japanese Laid-Open Patent Application (JP-A-Heisei 7-4724) describes "Method for Controlling And Saving Energy of Air Conditioning System". This conventional technique has the following feature. Air inside a room is sucked into an air conditioning apparatus through an air filter by a fan motor. A temperature of the sucked air is measured by an sensor set at a sucked air unit in the air conditioning apparatus. The air sucked into the air conditioning apparatus is cooled by a cooling unit, and again heated by a re-heating unit, and humidified by a humidifier, and then blown from the air conditioning apparatus. The temperature and the humidity of the blown air are measured by an sensor set outside the air conditioning apparatus. The wind quantity is controlled in accordance with a present wind rate and a temperature difference measured by the sensor set at a sucked air unit and the sensor set outside the air conditioning apparatus. The cooling quantity is controlled in accordance with the controlled wind quantity. Moreover, an open degree of a bypass damper for bypassing the air passed through the cooling unit is controlled in accordance with the humidity measured by the sensor set outside the air conditioning apparatus.
Japanese Laid-Open Patent Application (JP-A-Heisei 9-159239) describes "Clean Room". This conventional technique has the following feature. This is provided with a plate-shaped member with many holes set in the vicinity of a blowing port of FFU and an air releasing unit which is spaced away from the FFU and set substantially opposite to the FFU. An opening rate adjusted on the basis of the plate-shaped hole with the many holes is different depending on the set or non-set position of the FFU.
Japanese Laid Open Patent Application (JP-A-Heisei 9-287791) describes "Filter Unit And Clean Room Having Chamber". This conventional technique has the following feature. A plurality of FFUs are set removed, and a floor surface having an opening is placed in the clean room. The FFU is covered with a small chamber whose bottom surface is open and which is box-shaped and used for ceiling suck. An air intake is created around an air outtake of the FFU. A fan of the FFU is used to carry out the air blowout from the FFU and the air suck to the small chamber at the same time. It is possible to adjust a valve mounted at the air intake on a top surface of the small chamber to thereby adjust the balance between the quantity of the air suck from the ceiling and the quantity of the air suck to the small chamber.
Japanese Laid Open Patent Application (JP-A-Heisei 8-152170) describes "Structure of Clean Room". This conventional technique has the following feature. At first, a ceiling surface is made into an air filter surface provided with a plurality of air filters. Then, a clean room is created in which air is passed along a floor surface. Duct space for air circulation is disposed in portion outside the clean room. A cooling coil having a fan on a rear side thereof is set on a circulation path of the portion outside the clean room.